Fix memory leak caused by treating Code::next_code_link as strong in marker.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index f5504478036709908462cd0832dd9fa369e5f570..cda8b331717bc3fb5eaf17f8765913e51e1087f0 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1860,6 +1860,9 @@ class RootMarkingVisitor : public ObjectVisitor {
     for (Object** p = start; p < end; p++) MarkObjectByPointer(p);
   }
 
+  // Skip the weak next code link in a code object.
+  void VisitNextCodeLink(Object** p) { }

[Michael Starzinger, 2014/03/06 13:43:52]

This should actually be unreachable, because there is no "NextCodeLink" in the
root-set. There might be code objects in the root-set, but their body will be
visited using the static visitor (see line 1882) below. Can we add an
UNREACHABLE() assertion instead?

[ulan, 2014/03/13 14:06:52]

As discussed offline, this is called in ProcessTopOptimizedFrame. Added a
comment.

+
  private:
   void MarkObjectByPointer(Object** p) {
     if (!(*p)->IsHeapObject()) return;